fem: nastran solid element import - hypersizer

FEM: NASTRAN Solid Element Import

Collier Research Corporation Hampton, VA

© 2008 Collier Research Corp.

A New Capability Provided in 2009

• HyperSizer is able to import sandwich panelsHyperSizer is able to import sandwich panels defined in the FEM as NASTRAN CQUAD4 and CTRIA3 shell elements• Sh i th t lid• Shown in the next slide

• A new capability is to now be able to importA new capability is to now be able to import sandwich panels defined in the FEM as NASTRAN solid elements• Remaining slidesRemaining slides

© 2008 Collier Research Corporation

HyperSizer Can Import PCOMP and MAT8 Nastran Data for Sandwich Panels (Shell Element Modeling)

$ MSC.visualNastran for Windows Property 4 : Inner FacesheetPCOMP 4 0. 70. + + 54 0.0104 19.2 YES 54 0.0104 -19.2 YES+ + 54 0.0052 30.08 YES 54 0.0052 -30.08 YES+ + 54 0 0052 40 97 YES 54 0 0052 40 97 YES+I F h t + 54 0.0052 40.97 YES 54 0.0052 -40.97 YES+ + 54 0.0052 51.86 YES 54 0.0052 -51.86 YES+ + 54 0.0052 62.74 YES 54 0.0052 -62.74 YES+ + 54 0.0052 73.73 YES 54 0.0052 -73.63 YES+ + 54 0.0052 87.26 YES 54 0.0052 -87.26 YES

$ MSC.visualNastran for Windows Property 7 : Outer FacesheetPCOMP 7 0 70 +

Inner Facesheet

PCOMP 7 0. 70. + + 54 0.0052 45. YES 54 0.0052 -45. YES+ + 54 0.0052 90. YES 54 0.0052 0. YES+ + 54 0.0052 90. YES 54 0.0052 0. YES+ + 54 0.0052 90. YES 54 0.0052 -45. YES+ + 54 0.0052 45. YES

Outer Facesheet

$ MSC.visualNastran for Windows Material 54 : 2D Orthotropic MaterialMAT8* 54 22000000. 1900000. 0.3* 1190000. 1190000. 500000. 0.057* * -2.E-7 0.000012 70.

$ MSC.visualNastran for Windows Property 67 : Honeycomb Core

2D OrthotropicMaterial Property

$ p y yPSOLID* 67 56 3

$ MSC.visualNastran for Windows Material 56 : Honeycomb Core Material PropertiesMAT9* 56 45600. 0. 0.* 0. 0. 0. 100.* * 0. 0. 0. 0.* 100. 0. 0. 0.*

3D AnisotropicMaterial Property * 12600. 0. 0. 100.

* 0. 15700. 0.00174 0.* * 0. 0. 0. 0.* 0. 70.

Material PropertyCore

Solid Element Import: Contents

• Scope of Analysis and SizingScope of Analysis and Sizing

• Example Problem Description and HyperSizer p p ypSetup

• A l i R lt• Analysis Results

• Entering different material properties for TopEntering different material properties for Top and Bottom Facesheet Adhesives

• Assumptions and Limitations


Scope of Analysis d Si iand Sizing

Scope of Analyses and Sizing

• Any combination of a single solid element between two shell y gelements will be considered as a single honeycomb sandwich panel by HyperSizer.

• In HyperSizer’s graphics the solid element will not be shownIn HyperSizer s graphics, the solid element will not be shown. The shell elements for the top and bottom face will be shown as belonging to the same component (i.e. the same color)

• Solid elements can be either CHEXA or CPENTA elements as long as the shell elements are on opposite faces

• PSOLID import to a sandwich will only work if the sandwich isPSOLID import to a sandwich will only work if the sandwich is exactly one solid element thick. If multiple solid elements are stacked, or a solid has only one face or no faces, it will be ignored. Shell elements that are not identified as part of a PSOLID sandwich will be treated as bare laminatesPSOLID sandwich will be treated as bare laminates.

• Element Sizing results ( margins of safety, unit weight, etc.) will be shown on the shell elements. Facesheet results (such as


composite strength) will be shown on the corresponding facesheet, core results will be shown on both facesheets.

Example Problem D i ti d Description and HyperSizer Setupyp p

• The capabilities and setup of PSOLID import to HyperSizer

Solid Element Import Example

The capabilities and setup of PSOLID import to HyperSizer Sandwich components will be demonstrated in a simple example of a curved honeycomb sandwich panel in pure bending

Mx=1000 lb-in/in

1.25”Core Ribbon Direction

“B tt ” F h t

x

y

Shell Element Normals

“Bottom” Facesheet

3”

z

1 25” 3

1.25”

Mx=1000 lb-in/in

1.25”

“T ” F h t


Mx=1000 lb-in/in “Top” Facesheet

Solid Element Import Example Solid Element Orientation

Elements in the horizontal sandwich

x

z

Coord Sys ID = 6Elements in the horizontal sandwich are oriented by Coord Sys 5, those in the vertical leg by Coord Sys 6. Notice that in each case the z axis is normal to the facesheets

y

normal to the facesheets.

Elements in the curved portion are oriented by their local element axes.

zCoord Sys ID = 5

x

y


Solid Element Import Honeycomb Sandwich Properties

$ F ith NX N t P t 1 SOLID P t$ Femap with NX Nastran Property 1 : SOLID PropertyPSOLID 1 10 -1

$ Femap with NX Nastran Property 11 : SOLID PropertyPSOLID 11 10 6

PSOLIDs 1, 11, and 12 will be imported to HyperSizer as Component 1, 11, and 12.

$ Femap with NX Nastran Property 12 : SOLID PropertyPSOLID 12 10 5

$ Femap with NX Nastran Property 20 : LAMINATE Property

The third entry on the PSOLID card (blue outline) is the solid material direction. In PSOLID 1, the material direction corresponds

PCOMP 20 0. 364. HOFF 72. + + 20 0.0145 45. YES 20 0.0145 -45. YES+ + 30 0.0052 0. YES 30 0.0052 90. YES+ + 30 0.0052 0. YES 30 0.0052 45. YES+ + 30 0.0052 -45. YES 30 0.0052 -45. YES+ + 30 0.0052 45. YES 30 0.0052 0. YES+ + 30 0 0052 90 YES 30 0 0052 0 YES+

to the element material axes. PSOLIDs 11 and 12 are aligned with coordinate systems 6 and 5 respectively.

+ 30 0.0052 90. YES 30 0.0052 0. YES+ + 20 0.0145 -45. YES 20 0.0145 45. YES

$ Femap with NX Nastran Property 50 : LAMINATE PropertyPCOMP 50 0. 364. HOFF 72. + + 30 0.0052 45. YES 30 0.0052 -45. YES+

PCOMPs 20 and 50 will be imported and HyperSizer Laminate and La p materials+ 30 0.0052 0. YES 30 0.0052 90. YES+

+ 30 0.0052 0. YES 30 0.0052 0. YES+ + 30 0.0052 90. YES 30 0.0052 0. YES+ + 30 0.0052 -45. YES 30 0.0052 45. YES

Laminate and Layup materials will be created corresponding to these properties.



• The sandwich panel consists of a Hexcel honeycomb core

Top Face:

The sandwich panel consists of a Hexcel honeycomb core sandwich between two different laminates of AS4/3502 material

AS4/3502 Unidirectional Tape[ 45/-45/0/90/0]s

Core:Honeycomb: Hexcel 1/8-5052-.0010 (4.5 pcf)

Bottom Face: Hybrid laminateTape: AS4/3502 pFabric: AS4/3502-6S Fabric[ (±45)fabric/(0/90/0/+45/-45)tape]s



Several materials are included in the database for this example problem:

• Hexcel 1/8-5052-.0010 KMAT8%10This is the material that will be used as theThis is the material that will be used as the honeycomb core material in place of finite element MAT ID = 10

• Adhesive – Honeycomb Face – BottomAdh i H b F T• Adhesive – Honeycomb Face – Top

These two adhesive materials will be used to specify the bottom and top facesheet adhesive materials for flatwise tension and shear stress analysisy

• AS4/3502 Tape KMAT8%30• AS4/3502 Fabric KMAT8%20

Material properties that will be used as facesheetMaterial properties that will be used as facesheet composite materials in place of finite elementMATID = 30 and MAT ID = 20 respectively


HyperSizer Imported Material Properties Assigned to Top and Bottom Facesheet Variables

On import HyperSizer has

Top Face

On import, HyperSizer has automatically generated layups and laminates from the PCOMP properties in the FEM and assigned them to the gtop face, core and bottom face variables in HyperSizer

Note that the bottom face is a “Hybrid”

Core

Note that the bottom face is a Hybrid laminate therefore a HyperSizer “laminate” material is used rather than a layup as in the top face.

Bottom Face


Example Problem Imported FEM

Three components are imported from the Finite Element model corresponding to three different PSOLID Element Properties:Component 11

Top FaceComponent 11Bottom Face

The ordering of the top and bottom face of the sandwich components are dictated by the normal vectors on the elements.

The bottom face is the face which is away from the direction of the element normals.

Component 1Bottom Face

Component 12Bottom Face

In the example shown, the element normals are pointing out of the curved panel, therefore the bottom face of each component is the inner face of the radius ofComponent 1 the inner face of the radius of curvature.

Top FaceComponent 12Top Face


Analysis Results

Loading: Ny Membrane Load from FEM

x

y

z


Loading: Through-Thickness Stress Displayed on Solid Elements

FEA Results for solid core Flatwise Tension (z-z) Stress

Note that the solid element stresses will not be displayed in the HyperSizer interface, rather they are displayed on the facesheets as shown on the following slide.


Loading: Flatwise Tension Stress at each Facesheet

These are the controlling flatwise tension stresses from HyperSizer which i l d th li dinclude the applied ultimate load factor (1.5)


Controlling Failure Analyses

In the curved portion of the panel, flatwise tension is the controlling failure analysis.

In the flat portions, the analysis is controlled by composite strength.

Note, the top and bottom facesheets are in compression and tension respectively, therefore they havetherefore, they have different controlling failure mechanisms.


Minimum Margins of Safety

The flatwise tension stresses and margins of safety are essentially the same for the top and b tt f h tbottom facesheet.

This is because the allowables for the bottom and top face are pthe same.

The following section describes the process of assigning differentassigning different material properties to the bottom and top facesheet materials


Entering Different M t i l P ti f Material Properties for Top and Bottom Facesheet pAdhesives

Allowables for the Top and Bottom Facesheet Adhesive

• As imported, the flatwise tension and shear stress allowables areAs imported, the flatwise tension and shear stress allowables are assumed to be equal to the core tensile and shear allowables which are specified as part of the honeycomb material.

• In Version 5.5, you can now create isotropic materials that have “Adhesive” material properties which can be assigned separately to“Adhesive” material properties, which can be assigned separately to the top and bottom facesheets to better represent flatwise tension and shear allowables


• Two materials are included in the example database which can be

Allowables for the Top and Bottom Facesheet Adhesive

Two materials are included in the example database which can be used for adhesive properties

• To showcase the results, these two isotropic materials have allowables that are different from those of the honeycomb coreallowables that are different from those of the honeycomb core

Honeycomb Core Allowables

Bottom Face Adhesive Allowables

Top Face Adhesive Allowables


Scope of Analyses and Sizing

• Before these materials can be used by a sandwich, they must beBefore these materials can be used by a sandwich, they must be made “available” to the project. This is done on the Project Available Materials form:

From the Database Explorer Tree expandExplorer Tree, expand Available Materials, select the Isotropic Branch, and press “Select Materials”

S l t th t dh iSelect the two adhesive materials and press the “Apply” then OK buttons


• The materials are assigned to the sandwich facesheets on the

Scope of Analyses and SizingThe materials are assigned to the sandwich facesheets on the Sizing Form | Options Tab:

• For each facesheet, assign a thickness and a material:

Note: Adhesive thickness currently


yhas no effect on the analysis –It is included for future use

• Assign the top facesheet material to all components in the project

Scope of Analyses and SizingAssign the top facesheet material to all components in the project by right-clicking on the material and selecting “Assign Selection to All Groups in Project”

Right Click HereRight Click Here

• Repeat this operation by right clicking on the bottom face material and again assign this material to all groups in the project

Click OK

material and again assign this material to all groups in the project


Minimum Margins of Safety after changing facesheet adhesive properties

The top and bottom faces have the same flatwise tensile stresses, however their different adhesivedifferent adhesive allowables yield different margins of safety

T FBottom FaceMargin = -0.11

Top Face:Ffwt = 506 psifwt = 342 psi

MS = 506/342 – 1= 0.48

Bottom Face:F = 304 psi

Top FaceMargin = 0.48

Ffwt = 304 psifwt = 342 psi

MS = 304/342 – 1 = -0.11


Assumptions and Li it tiLimitations

Assumptions and Limitations

• Solid element alignment is assumed to be consistent withSolid element alignment is assumed to be consistent with material orientation• The orientation of the solid element material axes are assumed to be

a modelers responsibility• The FEA stresses for solid elements extracted from the F06 file are• The FEA stresses for solid elements extracted from the F06 file are

not transformed in any way. • The solid material z-axis is assumed to be the core through-thickness direction • The solid material x-axis is assumed to be the core longitudinal (ribbon) direction• The solid material y-axis is assumed to be the core transverse direction e so d ate a y a s s assu ed to be t e co e t a s e se d ect o

• Flatwise tension stress is assumed to be equal to the solid material zz stress

• If th t d fi d b lid l t ith t h ll• If the component defined by a solid element with two shell elements is assigned to any panel concept other than sandwich, an error will occur • For example if you use try to use this component to model a hatFor example, if you use try to use this component to model a hat

stiffened panel or an unstiffened panel, HyperSizer will return and error


Assumptions and Limitations

• EXPORT of material properties for a PSOLID sandwich willEXPORT of material properties for a PSOLID sandwich will not accurately capture the sandwich stiffness properties• Core material properties are not exported to a MAT9 card• Core thickness cannot be changed because it is tied to the element

thicknessthickness• This means that this capability is currently useful for calculating

sandwich margins for a given design, but should not be used for sizing of a sandwich panel where iteration with FEA is required.

• The in-plane stiffness (E, G) and allowable material properties (Fty, Fsy) of the adhesive material are ignored by the flatwise tension and shear analyses, only theby the flatwise tension and shear analyses, only the flatwise stress allowables are used

• If a material is chosen as a facesheet adhesive material with no adhesive allowables, margins of safety for flatwise tension and shear will be reported as “Data Reqd” HyperSizer treats this value as a negative margin of safety


fem: nastran solid element import - hypersizer

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